One day Rumi was reading next to a large stack of books. Shams Tabriz, passing by, asked him, "What are you doing?" Rumi scoffingly replied, "Something you cannot understand." On hearing this, Shams threw the stack of books into a nearby pool of water. Rumi hastily rescued the books and to his surprise they were all dry. Rumi then asked Shams, "What is this?" To which Shams replied, "Mowlana, this is what you cannot understand."
A second version of the tale has Shams passing by Rumi who again is reading a book. Rumi regards him as an uneducated stranger. Shams asks Rumi what he is doing, to which Rumi replies, "Something that you do not understand!" At that moment, the books suddenly catch fire and Rumi asks Shams to explain what happened. His reply was, "Something you do not understand."[9]From Wikipedia

Interesting to note that Rumi was roughly 37 (close to 40 for the sake of my implied point).

مولوی هرگز نشد مولا ی روم تا غلام شمس تبریزی نشد

Maulavi Rumi could never be Maulavi
If he had not devoted himself to Shams of Tabriz.